Computational study on use of single-point analysis method for quantitating local cerebral blood flow in mice

The benefits of a mouse model are efficiency and availability of transgenics/ knockouts. Quantitation of cerebral blood in small animals is difficult because the cannulation procedure may introduce errors. The [14C]-iodoantipyrine autoradiography (IAP) method requires both the tissue concentration and the time course of arterial concentration of the [14C] radioactive tracer. A single point-analysis technique was evaluated for measuring blood flow in mice (30 g +/- 0.3 g; n = 11) by using computational models of sensitivity analysis, which quantitates relationships between the predictions of a model and its parameters. Using [14C]-IAP in conjunction with mathematical algorithms and assumed arterial concentration-versus-time profiles, cortical blood flow was deduced from single-point measurements of the arterial tracer concentration. The data showed the arterial concentration profile that produced the most realistic blood flows (1.6 +/- 0.4; mean +/- SD, ml/g/min) was a profile with a ramp time of 30 sec followed by a constant value over the remaining time period of 30 sec. Sensitivity analysis showed that the total experimental time period was a more important parameter than the lag period and the ramp period. Thus, it appears that the accuracy of the assumption of linearly increasing arterial concentration depends on the experimental time period and the final arterial [14C]-iodoantipyrine concentration.